powerc/mm/hash: Reduce hash_mm_context size

Allocate subpage protect related variables only if we use the feature.
This helps in reducing the hash related mm context struct by around 4K

Before the patch
sizeof(struct hash_mm_context)  = 8288

After the patch
sizeof(struct hash_mm_context) = 4160

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
index 4481bedbb5beae476ec039b270b9f8b105a2bf90..eeb40091b46be4e4e64ea53c3ef3b2b55ad6b90d 100644 (file)
--- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
@@ -687,10 +687,8 @@ struct subpage_prot_table {
 #define SBP_L3_SHIFT           (SBP_L2_SHIFT + SBP_L2_BITS)
 
 extern void subpage_prot_free(struct mm_struct *mm);
-extern void subpage_prot_init_new_context(struct mm_struct *mm);
 #else
 static inline void subpage_prot_free(struct mm_struct *mm) {}
-static inline void subpage_prot_init_new_context(struct mm_struct *mm) { }
 #endif /* CONFIG_PPC_SUBPAGE_PROT */
 
 /*
@@ -720,7 +718,7 @@ struct hash_mm_context {
 #endif
 
 #ifdef CONFIG_PPC_SUBPAGE_PROT
-       struct subpage_prot_table spt;
+       struct subpage_prot_table *spt;
 #endif /* CONFIG_PPC_SUBPAGE_PROT */
 };
 

diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h
index e510e46b07ced57ac99bdfc2806c68fd23f35036..230a9dec7677484b1ba58afcc5b55ab8f7ba53fc 100644 (file)
--- a/arch/powerpc/include/asm/book3s/64/mmu.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu.h
@@ -206,7 +206,7 @@ static inline struct slice_mask *mm_ctx_slice_mask_16g(mm_context_t *ctx)
 #ifdef CONFIG_PPC_SUBPAGE_PROT
 static inline struct subpage_prot_table *mm_ctx_subpage_prot(mm_context_t *ctx)
 {
-       return &ctx->hash_context->spt;
+       return ctx->hash_context->spt;
 }
 #endif
 

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 27239a07677354baff7f42f5483fe296b496f1ab..6a2d315495a3c68517ce9e1831ba6e21d3156d2f 100644 (file)
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -1150,6 +1150,9 @@ static int subpage_protection(struct mm_struct *mm, unsigned long ea)
        u32 spp = 0;
        u32 **sbpm, *sbpp;
 
+       if (!spt)
+               return 0;
+
        if (ea >= spt->maxaddr)
                return 0;
        if (ea < 0x100000000UL) {

diff --git a/arch/powerpc/mm/mmu_context_book3s64.c b/arch/powerpc/mm/mmu_context_book3s64.c
index 6eef5a36b2e93da8e815dc616fd445321ac79a49..cb2b08635508b7cbff91a76504442e531a25a3f2 100644 (file)
--- a/arch/powerpc/mm/mmu_context_book3s64.c
+++ b/arch/powerpc/mm/mmu_context_book3s64.c
@@ -63,7 +63,8 @@ static int hash__init_new_context(struct mm_struct *mm)
        if (index < 0)
                return index;
 
-       mm->context.hash_context = kmalloc(sizeof(struct hash_mm_context), GFP_KERNEL);
+       mm->context.hash_context = kmalloc(sizeof(struct hash_mm_context),
+                                          GFP_KERNEL);
        if (!mm->context.hash_context) {
                ida_free(&mmu_context_ida, index);
                return -ENOMEM;
@@ -89,11 +90,21 @@ static int hash__init_new_context(struct mm_struct *mm)
        } else {
                /* This is fork. Copy hash_context details from current->mm */
                memcpy(mm->context.hash_context, current->mm->context.hash_context, sizeof(struct hash_mm_context));
+#ifdef CONFIG_PPC_SUBPAGE_PROT
+               /* inherit subpage prot detalis if we have one. */
+               if (current->mm->context.hash_context->spt) {
+                       mm->context.hash_context->spt = kmalloc(sizeof(struct subpage_prot_table),
+                                                               GFP_KERNEL);
+                       if (!mm->context.hash_context->spt) {
+                               ida_free(&mmu_context_ida, index);
+                               kfree(mm->context.hash_context);
+                               return -ENOMEM;
+                       }
+               }
+#endif
 
        }
 
-       subpage_prot_init_new_context(mm);
-
        pkey_mm_init(mm);
        return index;
 }

diff --git a/arch/powerpc/mm/subpage-prot.c b/arch/powerpc/mm/subpage-prot.c
index c72252542210d6f9f46ed45b64b5e0a1512b845f..c9dff4e1f295c05581d54ce323032e5b8a8494d7 100644 (file)
--- a/arch/powerpc/mm/subpage-prot.c
+++ b/arch/powerpc/mm/subpage-prot.c
@@ -29,6 +29,9 @@ void subpage_prot_free(struct mm_struct *mm)
        unsigned long i, j, addr;
        u32 **p;
 
+       if (!spt)
+               return;
+
        for (i = 0; i < 4; ++i) {
                if (spt->low_prot[i]) {
                        free_page((unsigned long)spt->low_prot[i]);
@@ -48,13 +51,7 @@ void subpage_prot_free(struct mm_struct *mm)
                free_page((unsigned long)p);
        }
        spt->maxaddr = 0;
-}
-
-void subpage_prot_init_new_context(struct mm_struct *mm)
-{
-       struct subpage_prot_table *spt = mm_ctx_subpage_prot(&mm->context);
-
-       memset(spt, 0, sizeof(*spt));
+       kfree(spt);
 }
 
 static void hpte_flush_range(struct mm_struct *mm, unsigned long addr,
@@ -99,6 +96,9 @@ static void subpage_prot_clear(unsigned long addr, unsigned long len)
        size_t nw;
        unsigned long next, limit;
 
+       if (!spt)
+               return ;
+
        down_write(&mm->mmap_sem);
        limit = addr + len;
        if (limit > spt->maxaddr)
@@ -218,6 +218,20 @@ SYSCALL_DEFINE3(subpage_prot, unsigned long, addr,
                return -EFAULT;
 
        down_write(&mm->mmap_sem);
+
+       if (!spt) {
+               /*
+                * Allocate subpage prot table if not already done.
+                * Do this with mmap_sem held
+                */
+               spt = kzalloc(sizeof(struct subpage_prot_table), GFP_KERNEL);
+               if (!spt) {
+                       err = -ENOMEM;
+                       goto out;
+               }
+               mm->context.hash_context->spt = spt;
+       }
+
        subpage_mark_vma_nohuge(mm, addr, len);
        for (limit = addr + len; addr < limit; addr = next) {
                next = pmd_addr_end(addr, limit);